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PETG Support

Posted: Fri Feb 28, 2020 9:33 am
by drthomasw3
I have finally dialed in most of the settings for PETG on my machine. Nice prints no stringing. However, I cannot get the support to stick to previously just printed surface. I have tried with and without using the part cooling fan. The supports start 8 hours into the print so this is getting expensive and frustrating. I am using a .4mm nozzle, hot-end 240 degrees, and 85-degree bed temp.
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Re: PETG Support

Posted: Fri Feb 28, 2020 3:33 pm
by S3D-Chris
Can you please post your factory file so we can look into this further.

Re: PETG Support

Posted: Fri Feb 28, 2020 9:56 pm
by drthomasw3
TouchScreenCase2Edge.factory
(84.92 KiB) Downloaded 587 times

Re: PETG Support

Posted: Sat Feb 29, 2020 12:09 pm
by TN Yankee
Just FYI, I've had pretty good luck with PETG supports. Some geometries work better than others, of course. I created a virtual extruder, so I could have really different parameters if needed.

With a 0.4 nozzle, I typically run EW at 0.50, including supports, but I have run them down to 0.40. I also drop the EM down to 0.70 (I don't recall if I've tried lower or not). Choose the virtual extruder on the support tab. I run 30% infill, inflation only rarely, support base layer of 1 if the support's contact area is pretty small, and combine every layer. Under Dense Support, again choose the virtual extruder, and 2 dense support layers at 70% infill.

Horizontal offset is 0.70, with a single separation layer for upper & lower. Angles are usually 45 & -45, but those will change depending on geometry.

HTH

Re: PETG Support

Posted: Sun Mar 01, 2020 4:14 pm
by drthomasw3
Thank you for the advice. I set up a virtual extruder as you suggested. I then printed the support test 3mm from Thingiverse so as not to waste time and material. The print was perfect, smooth, with sharp corners. The supports, however, were a total no go. they just did not stick to the previously printed. layers.

The same settings with the exception of bed size result in a perfect print on my MP Mini.

Re: PETG Support

Posted: Sun Mar 01, 2020 8:16 pm
by TN Yankee
Sorry to hear that. Its possible that some of the difficulties might be due to differences in PETG formulations between brands. I use those settings with some old MakerGeeks filaments, as well as newer SnoLabs (though I have some silver Veracity that requires at least 250C). Also, I typically run PETG around 240C, increasing to 250 on larger parts. Fan is minimal, though I do increase it a lot on bridging (as it usually would be over supports). It would be great to be able to run a custom (high) fan speed over the top layer of supports before running the next layer, but as of right now, that would require extensive hand coding.

Re: PETG Support

Posted: Sun Mar 01, 2020 8:23 pm
by arhi
drthomasw3 wrote:
Fri Feb 28, 2020 9:33 am
I cannot get the support to stick to previously just printed surface.
uh, I can't get PETG to easily unstick to previously printed surface (or from surface printed on top of support to unstick from support) :D

Are you sure that's PETG, PETG is one of the stickiest plastics we deal with, it sticks to everything too god

Re: PETG Support

Posted: Mon Mar 02, 2020 11:04 am
by drthomasw3
That is what I said! The issue I believe comes from the (Separation from Part) "Upper vertical Separation Layers" under the Support Tab, my value is 1. I assume this to mean 1 layer is skipped to minimize adhesion thus allowing separation of supports later. This separation is enough regardless of the sticking potential of PETG to facilitate spontaneous layer separation (model to support) in my case the part is 300mm by 200mm. Where the bed is much smaller MP Mini I used the same settings to print successfully 6 rolls of PETG and that is with part cooling. On a large part, all bets are off probably because the surface temperature of the part is significantly lower than the original bed temp and the hot end to surface distance is greater x2 the ideal print height. The result is no stick instead of the desired "weaker stick." I have not been able to figure out how to overcome this in the Simplify3D support settings. That is why I have posted my question here.
TN Yankee presented the best workaround using the virtual hot end. I just cannot seem to sneak up on the right setting combinations that work with this very large piece. I have printed the Support Test part from Thingiverse successfully on the larger machine, however, the larger print is still a no go.
the next obvious change would be to increase the extruded material temperature for the first support layer using the virtual extruder. But I have questions. If I add a virtual extruder in the Temperature tab I must also add a Temperature Identifier which I assume will not be recognized by my Rip Rap config.g secondly how do I specify the layer for this temp change to start and stop?
Other slicers seem to have taken this scenario into consideration in their advanced setting. :?:

Re: PETG Support

Posted: Mon Mar 02, 2020 11:13 pm
by drthomasw3
Cura does allow one to specify the z height for supports thus negating the need for increasing the temperature. So I am going to try that. If support settings are not going to be an improved feature in Ver 5 then I guess that I am out. Does Simplify monitor this community board????
Thanks, TN Yankee, for your time, advice and help.

Re: PETG Support

Posted: Tue Mar 10, 2020 9:29 pm
by drthomasw3
Well, Cura was the answer. Problem solved. So, I for one will not be wasting my money on a Simplify update. My current version of Simplify 3D does not even begin to compare to the latest version of Cura. Online support and documentation is also much better. Good luck to all. I am out of here!!!!!!